1. Field
Embodiments described herein relate generally to a semiconductor integrated circuit, and particularly to a semiconductor integrated circuit including a monitor circuit for monitoring characteristic of a semiconductor chip.
2. Description of the Related Art
Various kinds of measuring devices are already known as a configuration for measuring performance of a semiconductor integrated circuit formed on a semiconductor substrate.
In addition, a device is also known that measures characteristic (e.g., leakage current) of transistors in a semiconductor integrated circuit, and based on the measurement result, controls a supply voltage and a substrate bias of the semiconductor integrated circuit to suppress dispersion between the transistors in the characteristic.
As a method for measuring characteristic of transistors formed on a semiconductor substrate, a method of providing a four-terminal transistor to function as a process monitor on a dicing line of a chip is sometimes used. However, according to this method, it is necessary to provide a dedicated measuring device outside the chip. The dedicated measuring device is configured to connect to a transistor on the dicing line to measure performance of the transistors. Moreover, this method has a problem that it is difficult to specify the position of the transistor after the chip is diced.
Hence, as a method for measuring performance of transistors, there is used a method of providing a monitor circuit configured as a ring oscillator or a delay chain on the chip together with a semiconductor integrated circuit. However, a measuring device that measures characteristic of transistors by using a ring oscillator is influenced by the rise time and fall time of both NMOS transistors and PMOS transistors . Therefore, this device cannot detect characteristic of NMOS transistors and PMOS transistors separately.